Power assistive device for hand rehabilitation and a method of using the same

ABSTRACT

A power assistive device (100) for hand rehabilitation that provides training of a combined movement of finger flexion-extension and forearm supination-pronation to a user. The power assistive device (100) includes a hand brace (102) and a base (104). The hand brace (102) includes finger driving units (206) that adjustably connect to a platform (202, 204), actuators (208) that connect to the finger driving units (206), and force sensors (232) that connect to the finger driving units (206) and the bottom of the hand brace (102) and detect force signals generated by movement of the hand brace (102). The base (104) removably connects to the hand brace (102) and includes a supporting structure (302), a forearm rotator (110) that includes C-shaped tracks (314, 316) formed along an inner circumferential surface, a rotatable platform (306) that moves along the C-shaped tracks (314, 316), a mounting platform (308) that connects to the rotatable platform (306), and an electromyography (EMG) sensor (402A-402B) that attaches to the upper arm or forearm of the user and senses EMG signals generated by the user.

FIELD OF THE INVENTION

The present invention relates to a power assistive device for hand rehabilitation that provides training of finger flexion-extension and forearm supination-pronation to a user.

BACKGROUND

Power assistive devices have been widely used for hand rehabilitation. These devices often include a single sensor and provide training in a single degree of freedom. It may not be efficient and effective to use these devices to perform different types of training exercises.

In view of the demand for efficiently providing comprehensive trainings for hand rehabilitation, improvements in power assistive devices are desired.

SUMMARY OF THE INVENTION

One example embodiment is a power assistive device for hand rehabilitation that provides training of finger flexion-extension and forearm supination-pronation to a user. The power assistive device includes a hand brace and a base. The hand brace attaches to a hand of the user and includes a plurality of finger driving units that adjustably connect to a platform and that attach to fingers of the user, a plurality of actuators that connect to the finger driving units and that actuate the finger driving units, and a plurality of force sensors that connect to the finger driving units and the bottom of the hand brace and that detect force signals generated by movement of the hand brace. The base removably connects to the hand brace and includes a supporting structure that is located on a proximal end of the base and that supports a forearm of the user, a forearm rotator that abuts the forearm support and that includes a plurality of C-shaped tracks formed along an inner circumferential surface of the Forearm rotator, a rotatable platform that moves along the C-shaped tracks and that receives a forearm of the user, a mounting platform that connects to and extends from a distal end of the rotatable platform and that removably mounts the hand brace onto the base, and an electromyography (EMG) sensor that attaches to the forearm of the user and that senses EMG signals generated by movement of the upper limb of the user, in which the EMG signals and the force signals are used to provide the training of the finger flexion-extension and the forearm supination-pronation to the user.

Other example embodiments are discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a left perspective view of a power assistive device in accordance with an example embodiment.

FIG. 1B shows right perspective view of a power assistive device in accordance with an example embodiment.

FIG. 1C shows a left side view of a power assistive device in accordance with an example embodiment.

FIG. 2A shows a left perspective view of a dorsal side of a hand brace in accordance with an example embodiment.

FIG. 2B shows a left side view of a hand brace in accordance with an example embodiment.

FIG. 2C shows a right side view of a hand brace in accordance with an example embodiment.

FIG. 2D shows a bottom view of a hand brace in accordance with an example embodiment.

FIG. 3A shows an oblique view of a base in accordance with an example embodiment.

FIG. 3B shows a rear view of a base in accordance with an example embodiment.

FIG. 3C shows a top view of a base in accordance with an example embodiment.

FIG. 3D shows a bottom view of a base in accordance with an example embodiment.

FIG. 4A shows a side view of an upper limb wearing a power assistive device in accordance with an example embodiment.

FIG. 4B shows a side view of an upper limb wearing a power assistive device in accordance with an example embodiment.

FIG. 5 shows an electronic system that includes a power assistive device in accordance with an example embodiment.

FIG. 6 shows a method executed by a hand rehabilitation system to determine an onset time of muscle dynamics in accordance with an example embodiment.

FIG. 7 shows a method executed by a hand rehabilitation system to calculate an onset time of muscle dynamics in a hand rehabilitation system.

FIG. 8 shows a method executed by a hand rehabilitation system to determine an EMG onset time of muscle dynamics in accordance with an example embodiment.

FIG. 9 shows a method executed by a hand rehabilitation system to determine a force onset time of muscle dynamics in accordance with an example embodiment.

FIG. 10A shows an oblique view of a forearm rotator in accordance with an example embodiment.

FIG. 10B shows a rear view of a forearm rotator in accordance with an example embodiment.

FIG. 10C shows a side view of a forearm rotator in accordance with an example embodiment.

FIG. 10D shows a cross-sectional view of a forearm rotator along an E-E line of FIG. 10C in accordance with an example embodiment.

FIG. 11A shows an oblique view of a front finger follower in accordance with an example embodiment.

FIG. 11B shows a side view of a front finger follower in accordance with an example embodiment.

FIG. 12 shows a palm strap in accordance with an example embodiment.

FIG. 13A shows a dorsal view of a hand brace platform in accordance with an example embodiment.

FIG. 13B shows an inner view of a hand brace platform in accordance with an example embodiment.

DETAILED DESCRIPTION

Example embodiments relate to apparatus and method that provide training of finger flexion-extension and forearm supination-pronation to a user.

The use of surface electromyography (EMG) in a power assistive device for hand rehabilitation can provide important information on a motor unit neural activation and control in patients. The muscle fibre conduction velocity and EMG amplitude are two relevant parameters in surface EMG signal detection and processing. Meanwhile, mechanomyography (MMG) is useful as a non-invasive means to study muscle contractility in humans. Muscle contraction is accompanied by dimensional changes of the transverse diameter of the muscle fibres. These dimensional changes generate “in vivo” muscle surface oscillations, recordable by an appropriate probe placed over the muscle. When several motor units are active, a summation of surface oscillations generates a signal that has been labelled as surface MMG.

When an EMG sensor, an MMG sensor, and a force sensor are combined and processed synchronously, unique information about the electro-mechanical properties and motor control strategies during several types of muscle contractions can be acquired. When muscle is contracted the onset of each one of these comes in a physiological order in which EMG signals are the first, followed by MMG signals with force signals being the last to come. Even though the signal processing of all these three signals are carefully done, time delay between EMG signals and force signals with an onset of MMG in between, is usually around 40-50 milliseconds (ms). This is a very small time range but since all these three signals are incorporated and have very close onsets to each other, this time range can represent a real onset time of the muscle contraction. Such a precise measurement of the onset of the muscle contraction can provide unique information for robotic rehabilitation for patients. Reaction time measurement as a very relevant measurement parameter in robotics should be measured with a precise detection of muscle contraction onset, which can be made possible with integration of three sensors, e.g., EMG sensors, MMG sensors, and force sensors. For robotic purposes, even much larger time delays can be considered as an onset once the reliability (particularly Inter-Correlation-Coefficient) or repeatability without significant differences between measurements is shown to be under influence of many external factors.

An example embodiment includes a hand rehabilitation system that provides training of flexion-extension of fingers and supination-pronation of a forearm to a user. The system includes a hand brace, a base that removably connects to the hand brace, and an EMG sensor that attaches to either or both of an upper arm and a forearm of the user and senses EMG signals generated by the user.

In one example embodiment, the hand brace is wearable by the user and includes an external platform and an internal platform that connects to the external platform.

In one example embodiment, the hand brace includes a MMG sensor that attaches to either or both of an upper arm and forearm of the user and senses MMG signals generated by the user.

In an example embodiment, the hand brace includes finger driving units, actuators that connect to the finger driving units and actuate the finger driving units, force sensors that connect to the finger driving units and the bottom of the hand brace and detect force signals generated by movement of the hand brace.

In an example embodiment, the base includes a supporting structure located on a proximal end of the base, a forearm rotator abuts the supporting structure and includes C-shaped tracks formed along an inner circumferential surface of the forearm rotator, a rotatable platform that runs along the C-shaped tracks, and a mounting platform that connects to and extends from a distal end of the rotatable platform.

In another example embodiment, the rotatable platform receives and supports a forearm of the user by a mounting platform that removably receives the hand brace such that the hand brace removably mounts on the base.

In an example embodiment, the processing unit receives and analyses the EMG signals the force signals to determine an onset time of muscle dynamics of the upper limb of the user, so as to provide the training to the user.

In another example embodiment, the processing unit receives and analyses the EMG signals, the MMG signals, and the force signals to determine an onset time of muscle dynamics of the upper limb of the user, so as to provide the training to the user.

In one example embodiment, the rotatable platform rotates between a maximum supination position and a maximum pronation position. The rotatable platform supinates from a neutral position (i.e. a position where a thumb of the user faces upwards and is regarded as 0 degree) to a maximum of 45 degrees of supination (to an outer side) with respect to the neutral position at the maximum supination position. The rotatable platform pronates from the neutral position to a maximum of 90 degrees of pronation (to an inner side) with respect to the neutral position at the maximum pronation position.

In another example embodiment, the forearm base further includes a locking knob that screwably connects to the mounting platform. Further, the locking knob adjustably mounts the hand brace onto the mounting platform to fix a wrist of the user at three different positions when the user wears the hand brace and puts the forearm on the rotatable platform.

In one example embodiment, when the wrist is fixed at a first wrist extension position, the wrist rests at a neutral position of 0 degrees with respect to a longitudinal axis of the forearm of the user. When the wrist is fixed at a second wrist extension position, the wrist extends 15 degrees with respect to the longitudinal axis. When the wrist is fixed at a third wrist extension position, the wrist extends 30 degrees with respect to the longitudinal axis.

In an example embodiment, the base includes a position tracking sensor that tracks a movement route of the user on moving the base. In another example embodiment, the base includes an emergency stop button that enables the user to stop the base from operation to protect the user in case any unexpected malfunction of any part of the base.

In one example embodiment, the system includes a wireless receiver that receives commands from a smartphone, tablet, or other portable electronic device. By way of example, commands include actuating the finger driving unit for bending and extending fingers of the user, and rotating the rotatable platform along the C-shaped track for supinating and pronating the forearm of the user.

In an example embodiment, the EMG sensor is an EMG-MMG sensor that includes two EMG electrodes and a MMG sensor. The two EMG sensors are millimeters (20 mm) apart and sense the EMG signals. The MMG sensor locates between the two EMG electrodes and senses MMG signals.

In an example embodiment, a method to determine an onset time of muscle dynamics involves implementation of three different sensors, namely an EMG sensors, an MMG sensors, and a force sensors. An EMG onset time, an MMG onset time and a force onset time are determined from EMG signals sensed by the EMG sensors, MMG signals sensed by the MMG sensors and force signals sensed by the force sensors respectively. Time delays between the EMG onset times, the MMG onset times and the force onset times are then calculated and an average point will be considered as a real onset time of muscle dynamics, while voluntary movement is intended to be generated by the user.

By way of example, there are two EMG sensors applied in which one of the EMG sensors senses EMG signals for finger flexion and the other EMG sensor senses EMG signals for finger extension. There are also two MMG sensors applied in which one of the MMG sensors senses MMG signals for finger flexion and the other MMG sensor senses MMG signals for finger extension. Further, there are five force sensors applied in which each of the force sensors senses force signals of each of the fingers of the user.

In another example embodiment, there are two EMG sensors applied in which one of the EMG sensors senses EMG signals for forearm supination and the other EMG sensor senses EMG signals for forearm pronation. There are also two MMG sensors applied in which one of the MMG sensors senses MMG signals for forearm supination and the other MMG sensor senses MMG signals for forearm pronation. Further, there are five force sensors applied in which each of the force sensors senses force signals of each of the fingers of the user. There are also two other force sensors applied at the bottom of the hand brace to sense the force signal generated during forearm supination and pronation.

In an example embodiment, four parameters, namely T0, T1, T2, and rate of force development (RFD) are parameters in determining the time relationship of a complete muscle dynamics. By way of example, T0 is a time when an external stimulus applies to the system. T1 is an onset time of muscle dynamics and determined by a time averaged between the EMG onset time and the force onset time.

In one example embodiment, T1, the onset time of muscle dynamics, is determined by either a first average time between the EMG onset time and the force onset time, or a second average time between the MMG onset time and the force onset time. The choice of using either the first average time or the second average time as T1 depends on whether the EMG signals or the MMG signals are sensed first. If the EMG signals are sensed first, the first average time will be T1, while in case the MMG signals are sensed first, the second average time will be T1. By way of example, EMG signals are generally sensed earlier than the MMG signals.

By way of example, T2 is an onset time of muscle force threshold and is determined when the force exceeds a force threshold, for example, 5 Newtons (N) or 10 N. RFD is the rate of change or development of the force calculated starting from the force onset time to the force threshold.

As one example, an EMG signal threshold and/or a force signal threshold can be set as the muscle force threshold. In one example embodiment, the EMG signal muscle force threshold is set as the muscle force threshold at an acute stage after stroke. In another example embodiment, the force signal threshold is set as the muscle force threshold at a more chronic stage after stroke or when marked improvement can be seen and the patient is able to steer the force, for example, to manipulate an object.

FIGS. 1A-1C show a power assistive device 100 (hereinafter the “device”) that is used for hand rehabilitation in accordance with an example embodiment. The device 100 includes a hand brace 102 that removably connects to a base 104. A user suffering from upper-limb motor disability or upper-limb paralysis, or a stroke patient, can insert an affected hand into the hand brace 102 and rest a forearm of the affected hand on the base 104 for hand rehabilitation. By way of example, hand rehabilitation includes training of finger flexion-extension and forearm supination-pronation. In one embodiment, the device 100 is driven by electromyography (EMG) signals of the affected limb of the user, in which the EMG signals reflect an intention of the user to move the affected limb.

In an example embodiment, the hand brace 102 mounts on the base 104 at an inclination angle of ten degrees with respect to an axis X as shown in FIG. 1C. Under this inclination angle, a user can place his hand on the base in a natural position with minimal stress to his wrist joint on wearing the device 100.

FIGS. 2A-2D show a hand brace 200 of the device in accordance with an example embodiment. The hand brace 200 includes an external platform 202, an internal platform 204 that connects to an inner surface of the external platform 202, a plurality of finger driving units 206 that adjustably connect to the external platform 202 and the internal platform 204, a plurality of actuators 208 that moveably connect to the finger driving units 206, a plurality of actuator bases 210 that are fixed on an outer surface of the external platform 202 and connects to the actuators 208, and a side fixation bracket 212 that adjustably connect to the external platform 202 and the internal platform 204.

By way of example, the hand brace includes five finger driving units that adjustably connect to the external platform and the internal platform, five actuators that moveably connect to the five finger driving units respectively, and five actuator bases that are fixed on the outer surface of the external platform and connect to the five actuators respectively. The five actuators actuate the five finger driving units respectively.

In an example embodiment, upon wearing the hand brace 200, a dorsal side of a hand of the user is in contact with an inner side of the internal platform 204. By way of example, the internal platform 204 can be of different sizes to accommodate palms with different sizes.

In one example embodiment, the finger driving unit 206 movably mounts on the inner surface of the external platform 202 and extends outwardly from a distal end 214 of the external platform 202. The finger driving unit 206 includes an intermediate rail guide 224 at the distal end 214, a proximal rail guide 226 at a proximal end 220, an intermediate follower assembly 216 that connects the intermediate rail guide 224 and the proximal rail guide 226, and a proximal follower assembly 218 that connects the proximal rail guide 226 to the actuator 208. A front finger follower 256 connects to the intermediate follower assembly 216. The intermediate follower assembly 216 and the proximal follower assembly 218, respectively, ensures a controlled and proportioned angular rotation in a restricted range of a proximal interphalangeal (PIP) joint and a metacarpophalangeal (MCP) joint of the user, such that a movement and responsiveness of the hand brace 200 resembles a cohesive movement of a human finger specifically for hand opening action and hand grasping action.

In one example embodiment, a force sensor 232 is disposed on the front finger follower 256.

In an example embodiment, each of the intermediate rail guide 224 and the proximal rail guide 226 has an arc-shaped track 228. Bearings 230 are movably disposed within the track 228 so that the front finger follower 256 as driven by the intermediate follower assembly 216 and the proximal follower assembly 218, respectively, follow a path of the intermediate rail guide 224 along the track 228 and a path of the proximal rail guide 226 along the track 228. By way of example, a rotational range of the intermediate rail guide 224 and a rotational range of the proximal rail guide 226 are different, such that the intermediate follower assembly 216 and the proximal follower assembly 218 generate a proportional relationship between the intermediate rail guide 224 and the proximal rail guide 226. In one example embodiment, the hand brace 200 has a linkage assembly 222 that connects the intermediate follower assembly 216 and the proximal rail guide 226.

In one example embodiment, an intermediate strap holder 246 connects to a bottom side of the front finger follower 256, and a proximal strap holder 248 connects to a bottom side of the intermediate rail guide 224 and a bottom side of the proximal follower assembly 218. The intermediate strap holder 246 adjustably fixes a finger strap 250 through a strap position adjustable slot 252 that is disposed within a cavity of the intermediate strap holder 246. Likewise, the proximal strap holder 248 adjustably fixes a finger strap 250 through a strap position adjustable slot 252 that is disposed within a cavity of the proximal strap holder 248. By way of example, the intermediate strap holder 246 and the proximal strap holder 248 are made of soft pad. The finger strap 250 warps around the finger of the user to hold the finger within the finger driving unit 206 and keep the finger in contact while the finger driving unit 206 is moving.

The actuator 208 has a proximal end that connects to proximal end 220 of the external platform 202 through the actuator bases 210, and a distal end that connects to the proximal follower assembly 218. When the actuator 208 is actuated, a longitudinal motion of the actuator 208 is translated into an angular/rotational motion that causes relative rotation of the proximal follower assembly 218 along the track 228 of the proximal rail guide 226. The rotational movement of the proximal follower assembly 218 then actuates a rotational movement of the intermediate rail guide 224 in which when the intermediate rail guide 224 rotates, the intermediate follower assembly 216 rotates and pushes the front finger follower 256 to rotate along the track 228.

In one example embodiment, the hand brace 200 has a thumb platform 234 that is formed separately or integrally with the external platform 202. One of the finger driving units 206 that receives a thumb of the use, a thumb driving unit 236, adjustably connects to the thumb platform 234. By way of example, the thumb driving unit 236 adjustably connects to the thumb platform 234 at different positions to match different thumb lengths, different web sizes between the thumb and an index finger of the user. The thumb driving unit 236 includes a thumb rail guide 238, a thumb follower assembly 240 that connects the thumb rail guide 238 to the actuator 208. The thumb rail guide 238 has an arc-shaped thumb rail track 242. Thumb bearings 244 are moveably disposed within the thumb rail track 242 so that the thumb follower assembly 240 follow a path of the thumb rail guide 238 along the thumb rail track 242. A thumb strap holder 254 connects to a bottom side of the thumb rail guide 238 and adjustably fixes a finger strap 250 through a strap position adjustable slot 252 that is disposed within a cavity of the thumb strap holder 254. By way of example, the thumb strap holder 254 is made of a soft pad.

In an example embodiment, the actuator base 210 fixes onto the external platform 202 by, for example a screw set, at one end, and connects to the actuator 208 at the other end via, for example a hinge joint, at the other end. The actuator base 210 facilitates a proper alignment of the actuator 208, such that the actuator 208 and the finger driving unit 206 are properly aligned.

In one example embodiment, the side fixation bracket 212 adjustably connects to a little finger side of the external platform 202 at different lateral positions to match different palm sizes.

In an example embodiment, the force sensor 232 measures a resultant force generated by the finger of the user. By way of example, the resultant force generated has a range of magnitude of 0-50 N.

FIGS. 3A-3C show a base (or a forearm base) 300 of the device in accordance with an example embodiment. The base 300 includes a supporting structure 302, a forearm rotator 304 that abuts the supporting structure 302, a rotatable platform 306, and a mounting platform 308.

The supporting structure 302 locates at a proximal end 310 of the base 300 and receives a forearm of the user. A forearm strap 312 is adjustably located near an opening of the supporting structure 302. Once the forearm of the user is placed on the supporting structure 302, the forearm strap 312 can wrap around an upper surface of the forearm so as to secure the forearm onto the supporting structure 302.

The forearm rotator 304 abuts the supporting structure 302 and includes a track(s) formed along an inner circumferential surface of the forearm rotator 304 for the rotatable platform 306 to move therealong. In the example embodiment as shown, the forearm rotator 304 includes a first C-shaped track 314 and a second C-shaped track 316 that are formed along an inner circumferential surface of the forearm rotator 304. The rotatable platform 306 moves along the first C-shaped track 314 and the second C-shaped track 316 and receives a forearm of the user. The rotatable platform 306 moves in a clockwise direction to demonstrate a pronation action of the wrist, while an anti-clockwise movement of the rotatable platform 306 demonstrates a supination action of the wrist.

In another example embodiment, the forearm rotator can have more than two tracks that are formed along the inner circumferential surface of the forearm rotator for the rotatable platform to move therealong.

In an example embodiment, the rotatable platform 306 moves between a maximum supination position and a maximum pronation position. In one example embodiment, the maximum supination position and the maximum pronation position can be set by the user according to his/her needs. By way of example, the maximum supination position is pre-set at a position 45 degrees clockwise from a neutral position of (i.e. a position where a thumb of the user faces upwards and is regarded as 0 degree), and the maximum pronation position is pre-set at a position 90 degrees anti-clockwise from the neutral position of 0 degree. The rotatable platform 306 supinates (i.e. moves in a clockwise direction for a right hand) from a neutral position (i.e. 0 degree) up to 45 degrees with respect to the neutral position of the base 300 at the maximum supination position. The rotatable platform 306 pronates (i.e. moves in an anti-clockwise direction for a right hand) from the neutral position up to 90 degrees with respect to the neutral position of the base 300 at the maximum pronation position. In other words, the rotatable platform 306 can move clockwise from 0 to 90 degrees to demonstrate pronation of the wrist between 0 and 90 degrees, and can move anti-clockwise from 0 to 45 degrees to demonstrate supination of the wrist between 0 and 45 degrees.

The mounting platform 308 connects to and extends from a distal end 318 of the rotatable platform 306 and removably mounts a hand brace onto the base 300. By way of example, the mounting platform 308 is an L-shaped plate. A locking knob 320 removably connects to and securely locks at the mounting platform 308 at an extended end 322 of the mounting platform 308. By way of example, the locking knob 320 inserts into a hole on the extended end 322 of the mounting platform 308 to removably connect to the mounting platform 308.

In another example embodiment, the locking knob can have threads that match internal threads on a hole of the mounting platform, so that the locking knob can screwably connect to and securely locks at the mounting platform.

In an example embodiment, there are two interchangeable mounting platforms with two differently oriented mounting parts that mount the hand brace onto the base for left and right hands respectively.

The locking knob 320 adjustably mounts a hand brace of the device onto the mounting platform 308 and fixes a wrist of the user at different positions when the user is undergoing a training of finger extension and finger flexion. By way of example, the locking knob 320 fixes the wrist at three different positions. When the wrist is fixed at a first wrist extension position, the wrist rests at a neutral position of 0 degree with respect to a longitudinal axis of a forearm of the user. When the wrist is fixed at a second wrist extension position, the wrist extends 15 degrees with respect to the longitudinal axis of the forearm. When the wrist is fixed at a third wrist extension position, the wrist extends 30 degrees with respect to the longitudinal axis of the forearm.

In one example embodiment, the emergency stop button 326 is provided on a side of the base 300 and enables the user to stop the base 300 from operation to protect the user in case any unexpected malfunction of any part of the base 300.

In an example embodiment, a rechargeable battery 330 is removably provided on the distal end 318 of the base 300. By way of example, upon a full recharge, the rechargeable battery 330 enables the base 300 to run for four 25 hours continuously. By way of example, the rechargeable battery is a lithium-polymer battery.

FIG. 3D shows a bottom plate 328 of the base 300. In the example embodiment as shown, a plurality of bearing rollers 324 and a position tracking sensor 332 are provided on the bottom plate 328 of the base 300. By way of example, there are eight bearing rollers provided on the bottom part of the base. Bearing rollers 324 allow the base 300 to move smoothly on a surface where the base 300 sits on. The position tracking sensor 332 tracks a route of movement of the user on using the base 300. By way of example, the position tracking sensor 332 is a complementary metal oxide semiconductor (CMOS) sensor for position tracking so that the user is able to move over an area on using the base 300.

Referring back to FIG. 1A, flexion and extension of the fingers are exercised through the actions of finger driving units 106 of the hand brace 102, while supination and pronation of the forearm are exercised through the rotational movement of a rotatable platform 108 along an inner circumferential surface of a forearm rotator 110 of the base 104. In one example embodiment, the power assistive device 100 includes an actuator positioning controller that controls a speed of supination and pronation (i.e. a speed of the rotatable platform), so that a cycle time of supination/pronation is the same as a cycle time of flexion/extension to achieve synchronization between the finger driving units 106 and the rotatable platform 108.

In an example embodiment, when there is difficulty for the finger driving units 106 to move smoothly, for example due to a blockage to the finger driving units, the action of flexion or extension will stop and the finger driving units will return to an opposite direction in order to avoid any damages to the user and to the device 100.

In another embodiment, as a safety feature, a next cycle of finger flexion/extension and forearm supination/pronation will not start until both movements of the finger flexion/extension and forearm supination/pronation have completed. As such, synchronization between the finger driving units 106 and the rotatable platform 108 can be attained and no time shift between the two movements of the finger flexion/extension and forearm supination/pronation after several cycles can be ensured.

FIG. 4A shows a user that wears the device 400 in accordance with an example embodiment. Two electromyography (EMG) sensors 402A-402B removably attach to a forearm of the user. By way of example, the EMG sensor 402A removably attaches to a flexor digitorum muscle and EMG sensor 402B removably attaches to an extensor digitorum muscle.

FIG. 4B shows a user that wears the device 400 in accordance with another example embodiment. An electromyography (EMG) sensor 402A attaches to an upper arm of the user while 402B sensor attaches to a forearm of the user. By way of example, the EMG sensor 402A removably attaches to a Biceps Brachii muscle and EMG sensor 402B removably attaches to either flexor digitorum, extensor digitorum or pronator teres muscle in the forearm.

In an example embodiment, each of the EMG sensors 402A and 402B includes two EMG electrodes that are opposite in polarity. By way of example, the two EMG electrodes sense either finger flexion or finger extension if they are located on the forearm or if they belong to the EMG sensor 402A or the EMG sensor 402B. By way of example, the two EMG electrodes sense either forearm supination or forearm pronation if one of them is located on the upper arm and other one is located on the forearm, or if they belong to the EMG sensor 402A or the EMG sensor 402B. In other words, the two electrodes of the EMG sensor 402A do not detect different motions of the hand, and the two electrodes of the EMG sensor 402B do not detect different motions of the hand.

In one example embodiment, the EMG sensors are electromyography-mechanomyography (EMG-MMG) sensors that include two EMG electrodes and a MMG sensor. The two EMG electrodes are separate from each other by 20 millimeters (mm) and sense EMG signals. The MMG sensor is located between the two EMG electrodes and senses MMG signals. By way of example, one of the EMG electrodes senses EMG signals for finger flexion and the other EMG electrode senses EMG signals for finger extension. By way of example, one of the EMG electrodes senses EMG signals for forearm supination and the other EMG electrode senses EMG signal for forearm pronation. By way of example, the MMG sensor includes two MMG electrodes in which one of the MMG electrodes senses MMG signals for finger flexion and the other MMG electrode senses MMG signals for finger extension. By way of example, one of the MMG sensor includes two MMG electrodes in which one of the MMG electrodes senses MMG signals for forearm supination and the other MMG electrode senses MMG signals for forearm pronation.

In one example embodiment, a reference electrode can be mounted over an elbow of the user and provides a common reference to inputs of the two EMG electrodes.

The EMG sensors 402A-402B detect EMG signals generated by movement of a upper limb of the user. EMG signals from an affected muscle of a limb correspond to an intention of the user and can control an assistive motion provided by the device 400. As such, the user can actively participate in a training of a combined movement of finger flexion-extension and forearm supination-pronation. By way of example, the user can maintain finger flexion/extension while he supinates/pronates his forearm in the same training. If the user can maintain finger extension while supinating, flexor or spastic pattern is improved.

In one example embodiment, the EMG sensors are EMG-MMG sensors that also detect MMG signals generated by movement of a hand of the user.

In one example embodiment, in a training session(s), the actions of finger flexion, finger extension, forearm supination and forearm pronation can be combined in any forms and in any consequences per a demand and a need of the user.

FIG. 5 shows an electronic system 500 that includes the device 502 that communicates with a handheld portable electronic device (HPED) 516 via one or more network(s) 518 accordance with an example embodiment. The device 502 includes a hand brace 503 that removably connects to a base 504, an EMG sensor 506, a force sensor 508, a processing unit 510, a memory 512, and a transmitter/receiver 514. The processing unit 510 communicates with the hand brace 503 and the base 504, and receives EMG signals from the EMG sensor 506, and receives force signals from the force sensor 508. In an example embodiment, the EMG signals and the force signals are transmitted to the processing unit 510 in real time during training. The processing unit 510 analyses the EMG signals and the force signals to determine an onset time of muscle dynamics of a hand of the user. The processing unit 510 also communicates with the memory 512 and the transmitter/receiver 514. In one example embodiment, the memory 512 stores the EMG signals the force signals, and the onset time of muscle dynamics, and records movement histories of the hand brace 503 and the base 504.

In one example embodiment, the EMG sensor is an EMG-MMG sensor that senses both EMG signals and MMG signals. The EMG signals, the MMG signals and the force signals are transmitted to the processing unit in real time during training. The processing unit analyzes the EMG signals, the MMG signals and the force signals to determine an onset time of muscle dynamics of a hand of the user. The memory stores the EMG signals, the MMG signals, the force signals, and the onset time of muscle dynamics, and records movement histories of the hand brace and the base.

The transmitter/receiver 514 wirelessly receives commands from the HPED 516 to operate the device 502 for providing training of a combined movement of finger flexion-extension and forearm supination-pronation to the user. By way of example, the transmitter/receiver 514 receives commands form the HPED to actuate finger driving units of the hand brace 503 to provide a training of finger flexion and finger extension to the user. By way of example, the transmitter/receiver 514 receives commands form the HPED to move a rotatable platform of the base 504 to provide a training of forearm supination and forearm pronation to the user. In one example embodiment, the rotatable platform moves along C-shaped tracks of the base 504.

The HPED 516 (such as a smartphone, a tablet computer, a laptop, or other computer) can include a memory 528, a display 520, a device manager 522, a transmitter/receiver 524, and a processing unit 526. The memory 518 stores the information transmitted from the device 502. In an example embodiment, the information includes the EMG signals, the MMG signals, the force signals, the onset time of muscle dynamics, and a profile of the user. The display 520 displays the information and the device manager 522 (such as a software application) enables the user to communicate with the device 502, such as making commands to provide a training of finger flexion-extension and/or a training of forearm supination-pronation to the user. The transmitter/receiver 524 wirelessly transmits commands from the HPED to the device 502, and receives information stored in the memory 512 of the device 502.

FIG. 6 shows a method executed by a hand rehabilitation system to determine an onset time of muscle dynamics. Electromyography (EMG) signals of a hand of a user are sensed by an EMG sensor in a power assistive device in the hand rehabilitation system in box 602. Force signals of a finger of the hand of the user are sensed by a force sensor in the power assistive device in the hand rehabilitation system in box 604. The hand rehabilitation system calculates an EMG onset time from the EMG signals and a force onset time from the force signals in box 606. The hand rehabilitation system analyses the EMG onset time, and the force onset time to calculate the onset time of muscle dynamics in box 608.

In one example embodiment, mechanomyography (MMG) signals of the hand of the user are sensed by an MMG sensor in the power assistive device in the hand rehabilitation system. The hand rehabilitation system calculates an EMG onset time from the EMG signals, an MMG onset time from the MMG signals, and a force onset time from the force signals. The hand rehabilitation system analyses the EMG onset time, the MMG onset time, and the force onset time to calculate the onset time of muscle dynamics.

FIG. 7 shows a method to calculate an onset time of muscle dynamics in a hand rehabilitation system. The onset time of muscle dynamics is identified as the time averaged between an EMG onset time and a force onset timecalculated by the hand rehabilitation system in box 702.

In one example embodiment of a method to calculate an onset time of muscle dynamics in a hand rehabilitation system, a first average value between an EMG onset time and a force onset time is calculated by the hand rehabilitation system. A second average value between an MMG onset time and the force onset time is calculated by the hand rehabilitation system. The first average value is determined, by the hand rehabilitation system, to be the onset time of muscle dynamics if a first EMG signal is sensed earlier than a first MMG signal. The second average value is determined, by the hand rehabilitation system, to be the onset time of muscle dynamics if the first MMG signal is sensed earlier than the first EMG signal.

FIG. 8 shows a method to determine an EMG onset time in a hand rehabilitation system. The hand rehabilitation system calculates a value of three standard deviations (SD) for EMG signals from the EMG signals sensed by an EMG sensor in box 802. The hand rehabilitation system determines an EMG onset signal when an EMG signal reaches the three SD for EMG signals in box 804. The hand rehabilitation system determines the EMG onset time by identifying a time at which the EMG onset signal is sensed in box 806.

FIG. 9 shows a method to determine a force onset time in a hand rehabilitation system. The hand rehabilitation system calculates a value of three standard deviations (SD) for force signals from the force signals sensed by a force sensor in box 902. The hand rehabilitation system determines a force onset signal when a force signal reaches the three SD for force signals in box 904. The hand rehabilitation system determines the force onset time by identifying a time at which the force onset signal is sensed in box 906.

In an example embodiment, a method to determine an MMG onset time in a hand rehabilitation system is provided. The hand rehabilitation system calculates a value of three standard deviations (SD) for MMG signals from the MMG signals sensed by an MMG sensor. The hand rehabilitation system determines an MMG onset signal when a MMG signal reaches the three SD for MMG signals. The hand rehabilitation system determines the MMG onset time by identifying a time at which the MMG onset signal is sensed.

FIGS. 10A to 10D show an internal structure of a forearm rotator 1000 in accordance with an example embodiment. The forearm rotator 1000 includes a front plate 1002 and a back plate 1004 connects to the front plate 1002 through connecting rods 1006A-1006F and a U-shaped connecting plate 1008. A first C-shaped track 1010 is disposed on the front plate 1002 and includes a first rotary track 1014. A second C-shaped track 1012 is disposed on the back plate 1004 and includes a second rotary track 1020. Rotary bearings 1016A to 1016E are movably disposed within the first rotary track 1014 and the second rotary track 1020 to facilitate a rotational movement of a rotatable platform 1018 along the two rotary tracks 1014 and 1020. A forearm of the user rests on and secures onto the rotatable platform 1018 by, for example, a strap wrapping around the forearm so that the forearm rotates with the rotatable platform 1018. In an example embodiment, the rotatable platform 1018 moves in a clockwise direction to demonstrate a supination action of the wrist of a right hand, while an anti-clockwise movement of the rotatable platform 1018 demonstrates a pronation action of the wrist of the right hand. A mounting platform 1028 connects to a distal end of the rotatable platform 1018.

In one example embodiment, the bearings 1016A to 1016E connect to a spur-shaped gear ring 1022 and the gear ring 1022 engages with a motor gear 1024. During operation, a motor 1026 drives the motor gear 1024 to rotate in which teeth of the motor gear 1024 engages with teeth of the gear ring 1022 to drive a rotational movement of the gear ring 1022, the bearings 1016A to 1016E, and the rotatable platform 1018 along the two rotary tracks 1014 and 1020. The forearm of the user rotates as a result of the rotational movement of the rotatable platform 1018.

FIGS. 11A and 11B show a front finger follower 1100 in accordance with an example embodiment. A force sensor 1102 and a wire pad 1104 dispose on a flat section of the front finger follower 1100. By way of example, the force sensor is a film sensor.

In one example embodiment, the force sensor 1102 senses force signals generated by a finger of the user due to flexion/extension of the finger. The force signals then transmit through the first wires 1106A and 1106B to the wire pad 1104, and then transmits to a processing unit for analysis through second wires 1108A and 1108B.

In an example embodiment, the front finger follower 1100 includes a crack point 1110 disposed on a bottom side of the flat section of the front finger follower 1100. The crack point 1110 concentrates stress of the finger along a centre line of the crack point 1110. When the finger presses, the crack point 1110 closes and the force sensor 1102 extends. When the finger extends, the crack point 1110 opens and the force sensor 1102 contracts.

In one example embodiment, the front finger follower 1100 includes a slanted proximal end 1112 and a finger pad 1114 or a strap holder is placed at a bottom side of the slanted proximal end 1112. By way of example, a strap holder is an intermediate strap holder 246 or a proximal strap holder 248 as shown in FIG. 2B.

In another example embodiment, the front finger follower 1100 can rotate along a track (e.g. track 228 as shown in FIG. 2B) of a rail guide (e.g. an intermediate rail guide 224 as shown in FIG. 2B). By way of example, the rotational movement of the front finger follower 1100 is carried out by an interaction between a bearing that is movably disposed within a track (e.g. bearings 230 as shown in FIG. 2B) and holes 1116A to 1116B of the front finger follower 1100.

In an example embodiment, the force sensor 1102 measures a resultant force generated by the finger of the user. By way of example, the resultant force generated has a range of magnitude of 0-50 N.

FIG. 12 shows a palm strap 1200 in accordance with an example embodiment. In one example embodiment, the palm strap 1200 attaches to an internal platform of a hand brace (e.g. the internal platform 204 as shown in FIG. 2D) to fix a palm of user to the internal platform. By way of example, two palm straps are used to fix the palm to the internal platform more securely.

FIGS. 13A and 13B shows a hand brace platform 1300 in accordance with an example embodiment. In one example embodiment, the hand brace platform 1300 resembles an internal platform of a hand brace (e.g. the internal platform 204 as shown in FIG. 2D) that can be locked on an external platform of the hand brace (e.g. the external platform 202 as shown in FIG. 2A).

In one example embodiment, the hand brace platform 1300 includes brace force sensors 1302A and 1302B disposed on a first side 1304 of the hand brace platform 1300. The brace force sensors 1302A and 1302B detect force signals generated during supination and pronation.

In another example embodiment, the hand brace platform 1300 includes force pads 1306A and 1306B that are disposed on a second side 1308 of the hand brace platform 1300 and provide better sensation of the force generated during supination and pronation. Grooves are disposed on sides of the force pads 1302A and 1302B to create stress concentration therealong.

Examples of an EMG sensor include, but are not limited to, an EMG sensor, a MMG sensor, a combined sensor of EMG sensor and MMG sensor (i.e. an EMG-MMG sensor), a sensor in which a MMG sensor embeds between two EMG electrodes, and sensor includes two EMG electrodes with no MMG sensor.

As used herein, the term “connect” means that an element connects directly or indirectly to another element mechanically, electrically, or mechanically and electrically.

As used herein, an “actuator” converts electrical energy into mechanical energy to move finger driving units. Examples of an actuator include, but are not limited to, linear actuator.

As used herein, a “wireless transmission” is the transmission of information between two points not connected by an electrical connector. Examples of wireless transmission include, but not limited to, wi-fi transmission, Bluetooth transmission, radio frequency (RF) transmission, infrared (IR) transmission and 3rd generation (3G) or 4th generation (4G) of mobile telecommunications technology.

The methods and apparatus in accordance with example embodiments are provided as examples, and examples from one method or apparatus should not be construed to limit examples from another method or apparatus. Further, methods and apparatus discussed within different figures can be added to or exchanged with methods and apparatus in other figures. Further yet, specific numerical data values (such as specific quantities, numbers, categories, etc.) or other specific information should be interpreted as illustrative for discussing example embodiments. 

What is claimed is:
 1. A power assistive device for hand rehabilitation that provides training of a combined movement of finger flexion-extension and forearm supination-pronation to a user, the power assistive device comprising: a hand brace adapted to attach to a hand of the user and that includes: a plurality of finger driving units that adjustably connect to a platform and that is adapted to attach to fingers of the user; a plurality of actuators that connect to the finger driving units and that actuate the finger driving units; a plurality of force sensors that connect to the finger driving units and that detect force signals generated by movement of the finger driving units and a bottom of the hand brace; a base that removably connects to the hand brace and that includes: a supporting structure that is located on a proximal end of the base and that is adapted to support a forearm of the user; a forearm rotator that abuts the supporting structure and that includes a plurality of C-shaped tracks formed along an inner circumferential surface of the forearm rotator; a rotatable platform that moves along the C-shaped tracks and that is adapted to receive the forearm of the user; a mounting platform that connects to and extends from a distal end of the rotatable platform and that removably mounts the hand brace onto the base; and an electromyography (EMG) sensor that is adapted to attach to either or both of an upper arm and the forearm of the user and that senses EMG signals generated by movement of the upper arm or the forearm of the user; a processing unit that communicates with the hand brace and the base; wherein the EMG signals and the force signals are received and analysed by the said processing unit to determine an onset time of muscle dynamics of an upper limb of the user to provide the training of the combined movement of the finger flexion-extension and the forearm supination-pronation to the user.
 2. The power assistive device of claim 1, wherein the hand brace is wearable by the user and includes an external platform and an internal platform that connects to the external platform.
 3. The power assistive device of claim 1, wherein the rotatable platform moves between a maximum supination position and a maximum pronation position, with the neutral position defined as a position where a thumb of the user faces upwards.
 4. The power assistive device of claim 1, wherein the rotatable platform moves between a maximum supination position and a maximum pronation position, and the rotatable platform supinates from a neutral position to a maximum of 45 degrees with respect to the neutral position at the maximum supination position, and the rotatable platform pronates from the neutral position to a maximum of 90 degrees with respect to the neutral position at the maximum pronation position; wherein the neutral position is a position where a thumb of the user faces upwards and is regarded as 0 degree.
 5. The power assistive device of claim 1, wherein the base further includes: a locking knob that connects to the mounting platform through a hole on an extended end of the mounting platform, and that adjustably mounts the hand brace onto the mounting platform to fix a wrist of the user at different wrist extension positions with respect to a longitudinal axis of the forearm.
 6. The power assistive device of claim 1, wherein the base further includes: a locking knob that connects to the mounting platform through a hole on an extended end of the mounting platform, and that adjustably mounts the hand brace onto the mounting platform to fix a wrist of the user at three different wrist extension positions; wherein when the wrist is fixed at a first wrist extension position, the wrist rests at a neutral position of 0 degree with respect to a longitudinal axis of the forearm of the user, and when the wrist is fixed at a second wrist extension position, the wrist extends 15 degrees with respect to the longitudinal axis of the forearm, and when the wrist is fixed a third wrist extension position, the wrist extends 30 degrees with respect to the longitudinal axis of the forearm.
 7. The power assistive device of claim 1, wherein the base further includes: a plurality of bearing rollers that allow the base to move smoothly on a surface.
 8. The power assistive device of claim 1, wherein the base further includes: a position tracking sensor that tracks a route of movement of the user on using the power assistive device.
 9. The power assistive device of claim 1, further comprising: a wireless receiver that receives, from a handheld portable electronic device (HPED), commands to actuate the finger driving units for flexing and extending fingers of the user, and commands to move the rotatable platform along the C-shaped tracks for supinating and pronating the forearm of the user.
 10. The power assistive device of claim 1, further comprising: a mechanomyography (MMG) sensor that senses MMG signals of the upper arm or the forearm of a user; wherein the MMG signals are received and analysed by the processing unit with said EMG signals and force signals to determine an onset time of muscle dynamics to provide the training of the combined movement of the finger flexion-extension and the forearm supination-pronation to the user. 